Self-locking differential mechanism



March 11, 1941. E F|TZNER 2,234,591

SELF-LOCKING DIFFERENTIAL MECHANISM Filed Dec. 28, 1938 INVENT'OR fri/:s 5f.: ner

BY @4M y il ATTOREYS Patented Mar. 11, 1941 saar-Looms. n

Ernst Fitzner, Stuttgart-Wangen,

signor to Dr. ing. h.

lMechanism Germany, asc. F. Porsche K.G.,

Stuttgart-Zulfenhausem Germany, a company of Germany Application December 28, 1938, Serial No. 248,061

The present invention relates to improvements In Germany January 26, 1938 iz claims. (cl. 'J4-31.5)

in self-locking differential mechanism particularly for power vehicles and it has for an object toimprove such devices in which the internal friction is increased for the purpose of achieving the desired braking action.

Another object of the present invention is to the locking of the differential mechanism uponl rounding a curve is prevented so long as both transverse shafts transmit a certain amount of torque.

It is another object to providea construction in which-shocks upon the driving mechanism are avoided as by connecting the wheel driving shafts elastically with respect to their driving wheels.

Another object is to utilize such elastic means ing mechanism.

I for the purpose of actuating the differential lock,

According to the invention the relative movement permitted by the elastic member serves to actuate the differential locking device through operation of helical driving mechanism thus providing longitudinal movement relative to the transverse wheel driving shafts whereby the braking arrangement can be made exceptionally simple.

It is another object to provide such a construction in which the elastic members are arranged to transmit a part only of the maximum torque to be transmitted to its respective transverse shafts possibly one half or one fourth thereof, the balance being carried by an abutment which comes into action when the elastic members have been deformed.

It is another'object to provide a particularly simple form of construction in which the elastic action is in the direction of the axis of thetransverse wheel driving shafts.

Further objects and advantages ofthis invention will be apparent from consideration of the specification as illustrated by the accompanying drawing of possible embodim in whichl drawing:

ents of the invention,

Fig. 1 shows a vertical cross-sectional view of such a Fig. 2 shows a partial vertical cross-sectional view along the line II-II of Fig. 1 upon a somewhat enlarged scale; 5

Fig. 3 represents a development along the line III-III of Fig. 2; and

Fig. 4 shows another development along the line IV-IV of Fig. 2; whereas Figs. 5 and 6 show views similar to Fig. 4 butv illustrating other modified forms.

Referring to Fig. 1, the transverse shaft driving gears I, I' are, through the connecting sleeve shown, connected with the disks 2, 2' which serve to rotate the disks a end l' through the elastic 1l members 3, I' which', 'as shown have the form of helical springs (see also Fig. 2). Between the disks 2, 2' and 4, 4' are located the helical driving members 5, 5', attached or formed integrally with the disks 2, k2 and 4, 4' (see Fig. 4). The'f l outer driving disks 4, 4' are coupled with the sleeves 1, 1' by means of the splined connections 6. i'. Disks 4, 4'l are normally pressed by means of coil springs l, 8' which bear against the flange I, l' (of the sleeves 1, 1') and against the outer f 1 I and enclose the entire differential locking mechanism. With I2, I2' are connected the external 54'* clutch plates I3, I3' whereas 'the inner clutch I plates I4, I4' are located upon the projection housing II, II' toshafts IB and III'; by means'of 5 the gears I, I', the inner driving disks 2, 2', the elastic members 3, 3 to disks 4, 4' (and parallel thereto from the two halves II, II' of the rotat- -ing housing. the coupling drums l2, l2', the outer coupling plates I3, i3', the inner coupling plates 5 I4, I4', and the projections I5, I5', to the said outer driving disk 4, 4') from which the power transmission goes over the splined connections 6, I' to the sleeves l., 1' which finally are rigidly connected withthe sideshefts u, la'. l Now, if i which are effective in a circumferential direction.

torque is transmittedto the side shafts I0, I Il' the coil springs 3, 3' are first compressed (the play in the friction rings I3, I3 and Il, Il' and their mountinss permitting sufficient movement for this purpose) so that the inner driving disks 2, 2' rotate with respect to the outer drivingl disks 4, 4' whereby 4the helical parts 5, 5' become effective to press the outer driving disks I, l' outwardly -against the action ofv springs 8, 8', thus gradually relieving the coupling plates i3,- I3 and I4, I4' so that the differential mechanism becomes free to operate. If now, for example, the left side is unloaded (as when the left driving wheel is in sand), the coil spring 3 serves to reversely rotate the outer driving disk l relative to disk 2 whereby through the helical parts A5 and the coil spring 3 the braking mechanism of the left side is `made effective so that the shaft Il is caused to rotate at 'the speed of the housing H, I I', assuring that the shaft It' and the wheel driven therebywill also rotate.

In the form of the invention shown, the elastic members consist essentially of the springs 3, '3'

Taking into consideration the power transmissionirf ratios and the friction conditions with respect to the helical parts 5, 5' it will be seen that the coil springs! although working axially serve to assist said springs 3, 3'. Having Vthis thought in mind, it. is obvious that other forms of construction may be resorted to in which only one type of spring finds application which operates only in a rotary direction or only in an axial direction. Since only a small spring movement is necessary it is also possible to use leaf springs with advantage. Fig. 2 shows how the elastic coupling between the transverse shaft gear i and the shaft Il may be effected. The numeral i9 indicates a claw attached to the outer drive disk I which claw lies between the claws 2l of the inner driving disk 2 being held relative to the claws 23 by the! spring members 3. j

. According to Fig. 3 the claw I9 is formed with surfaces 2| and 22 which after deformation of the coil spring 3 to the desired predetermined extent come to rest against the surface 23 or 24 of the outer driving disk l (depending upon the direcfaces.

Fig. 5 shows another form of construction of the helical member for an arrangement in which. the locking of the differential occurs continuously in one direction of rotation. In said direction of rotation, a positive driving coupling is eifective through the surfaces 25 which comprise surfaces lying substantially in the longitudinal plane of the transmission, whereas for rotation in the opposite direction screw helical surfaces 5 are employed as in Fig. 4. It is, of course, obvious that with this form of construction the elastic members are provided only for elastic operation in one direction and the abutments, if present, are also supplied only for positive operation in one direction. y

In Fig. 6 is shown a modification designed for operation in both directions of rotation and operating by means of an intermediate member. As intermediate member balls 23 are provided which operate upon the surfaces 21, 23 formed by depressions in the inner driving disk 2 and the outer driving disk I, thus converting relative rotary motion of said disks into relative axial displacement.

Theneld of application of the invention is i contemplated primarily as in power vehicles but the invention may be utilized in all cases in which locking of a differential mechanism is to occur upon the absence of load upon one side, which may occur, for example, in machine tools, and dividing or calculating machines; irrespective of what type thel differential mechanism may take as, for example, whether it operates with bevel gears or spur gears. Other cases are contemplated in which the flow of power through the differential mechanism occurs in the reverse direction as where the power is applied through one or both of the transverse shafts. Further developments on the inventive concept are coning half axles.

It will be noted that the vconstructions shown and described will serve admirably to accomplish the objects stated above. It is to be understood, however, that the constructions disclosed `above are intended merely as illustrative of the invention and not as limiting as variousl modiiications therein may be madewithout departing from the invention as defined by a proper interpretationof the claims which follow.

I claim:

1. In a differential mechanism for power vehicles or the like, the combination -of a ring member, twov power delivery shafts, differential mechanism for delivering power from said ring member to said shaft.,coupling means for coupling said vring member to said shafts, which coupling means is normally effective, and means actuated by the application of torque as between the ring member androne of said shafts serving to disengage the coupling between said shaft and said ring member.

2. 'I'he combination according to claim 1 in which said coupling disabling means comprises an elastic driving member connected between said ring member and 'said shaft.

3. The combination according to claim l in which said coupling disabling means comprises an elastic driving member connected between said ring member and said shaft, and means actuated as an incident to the distortion of saidl elastic means to disengage said coupling.

4. The combination according to claim 1 in which said coupling disengaging means comprises an elastic driving member connected between said ring member and said shaft, and means actuated as the result of distortion of said elastic means to disable said coupling, said last mentioned means comprising two cooperating helical surfaces carried by the members between which said elastic member acts, so arranged that relative rotary movement of said members causes relative axial movement, and means actuated by said relative axial movement for disengaging said coupling.

5. In a differential mechanism for power vehicles or'the like, the combination of a housing, a power applying ring member mounted for rotation therein, two power delivery shafts, dif-,-

ferential mechanism for delivering power from said ring member to said shafts, normally effective coupling means for coupling said ring member to said shafts, and means actuated by the application of torque as between the ring member and one of said shafts serving to disringmember, said Vcoupling means comprising generally cylindrical extensions connected to and rotating with said ring member and serving as housings for the other parts of said coupling means and for said coupling disabling means.

6. The combination according to claim 1 in which said coupling diseng'afging' means comprises an elasticV driving` member connected between said ring member and said shaft and serving to transmit the entire torque applied to its respective shaft.

7. The comblnationgaccording to claim 1 in which said coupling disengaging means comprises an elastic driving member connected between 'said ring member and said shaft, and abutment means so constructed and arranged as to become effective upon application of a pre.

determined amount of torque to said elastic member, which abutment means serve to transamount. l

8. In a diierential mechanism for power vehicles or the like, the combination of a ring' member, two power delivery shafts, differential mechanism for delivering power from Ysaid ring member to said shafts, coupling means for coupling said ring member to saidV shafts for rotation therewith, which coupling means is normally effective, and means actuated by the application of torque in one direction only as between the ring member and one of said shafts mit any torque in excess of said predetermined serving to disengage the coupling between said shaft and said ring member..

9. The combination according tol claim l in which said coupling disengaging means. comprises an elastic driving member connected between said ring member and said shaft, and

means actuated as the result of distortion of said elastic means to disengage said coupling, said last mentioned means comprising two cooperating helical surfaces carried by the members between which-said elastic member' acts. so arranged that relative rotary movement of said member in one direction only causes relative axial movement, and means actuated by said A relative axial movement for disengaging said coupling.. y

ring member, said coupling 'means being located 3 10. In a differential mechanism. for. power vehicles or the like, the combination of a'housing, a powerapplying ring membermolmted for rotation therein, two power delivery Shafts, differential mechanism for-delivering power from said ring member to said shafts, normally effective coupling means for coupling said ring member to said shafts' for rotation therewith, and

means actuated by the application ofV torque as between 'the' ring member and one of said shafts serving to disengage the coupling between saidshaft and said ring member, said coupling-incansbeing located outside of said housing.-

11. 1n a' diaerential mechanism fg; power Vve hicles or thelike, the combination of aihousing, a power applying ring member mounted for ro'- tation therein, two power delivery shafts, dif--V ferential mechanism for delivering 'power from said ring member to said shafts, normally-'effective coupling means for coupling said ring 2.0

member to said shafts, and means actuated by the application of torque as between the ring member and one 'of said shafts serving to disable the coupling between said shaft-and said outside of said housing and comprising generally cylindrical extensions connected to and rotating with said ring member and serving as housings for the other parts of said coupling means and for said coupling disabling means.

12. The combination according to claim I, in which saidl coupling disabling means comprises an elastic drlvingjmember connected between said ring member and said shaft, and means actuated as the result of distortionof said elastic means to disable said coupling. said last mentionedmeans comprising two facing depressions in the members between which said'elastic member acts, and intermediate rolling members 1o- 'cated within said depressions, 'whereby relativev rotary movement -of-said members causes relative axial movement, and means actuated by said relative axial movement "for disabling said coupling. l Y 

